diff --git a/css/main.css b/css/main.css
index dff8f7ba..d987876a 100644
--- a/css/main.css
+++ b/css/main.css
@@ -507,6 +507,32 @@ html.has-sticks #stickCanvas {
 	display:block;
 }
 
+#mapContainer.no-gps-data:before {
+    position: absolute;
+    display: block;
+    top: 0;
+    right: 0;
+    bottom: 0;
+    left: 0;
+    z-index: 9999;
+    content: "";
+    background-color: gray;
+    opacity: .5;
+}
+
+#mapContainer.no-gps-data:after {
+    position: absolute;
+    display: block;
+    top: calc(30%);
+    right: 0;
+    bottom: 0;
+    left: 0;
+    z-index: 10001;
+    content: "No GPS Data";
+    text-align: center;
+    font-size: 3vw;
+}
+
 html.has-analyser-fullscreen.has-analyser .analyser input:not(.onlyFullScreenException) {
 	display:block;
 }
diff --git a/js/graph_map.js b/js/graph_map.js
index 0fe7e047..50bf8bd9 100644
--- a/js/graph_map.js
+++ b/js/graph_map.js
@@ -121,22 +121,27 @@ function MapGrapher() {
     }
 
     this.setFlightLogIndexs();
-
     let { latlngs, maxAlt, minAlt } = this.getPolylinesData();
 
-    const polyline = L.polyline(latlngs, polylineOptions);
+    const hasGpsData = latlngs.length > 0;
 
-    const polylineC = this.createAltitudeColoredPolyline(
-      latlngs,
-      maxAlt,
-      minAlt
-    );
+    if (hasGpsData) {
+      const polyline = L.polyline(latlngs, polylineOptions);
+
+      const polylineC = this.createAltitudeColoredPolyline(
+        latlngs,
+        maxAlt,
+        minAlt
+      );
 
-    trailLayers.set(logIndex, { polyline, polylineC });
+      trailLayers.set(logIndex, { polyline, polylineC });
 
-    if (latlngs.length > 0) {
       homePosition = this.getHomeCoordinatesFromFlightLog(flightLog);
+    } else {
+      console.debug("FlightLog has no gps data.");
     }
+
+    $("#mapContainer").toggleClass("no-gps-data", !hasGpsData);
   };
 
   this.setFlightLogIndexs = function () {
@@ -382,7 +387,7 @@ function MapGrapher() {
     const lng = frame[lngIndex];
     const alt = frame[altitudeIndex];
 
-    return typeof lat == "number" || typeof lng == "number"
+    return this.isNumber(lat) && this.isNumber(lng)
       ? L.latLng(
           lat / coordinateDivider,
           lng / coordinateDivider,
@@ -391,6 +396,10 @@ function MapGrapher() {
       : null;
   };
 
+  this.isNumber = function (n) {
+    return typeof n === "number" && !isNaN(n);
+  };
+
   this.getGroundCourseFromFrame = function (frame, groundCourseIndex) {
     const gc = frame[groundCourseIndex];
     return typeof gc == "number" ? gc / grounCourseDivider : 0;